1. Field of the Invention
This invention is directed toward a fluid circulating system capable of selective temperature control primarily designed for use in combination with a thermal blanklet or pad wherein both heating and cooling effects may be produced.
2. Description of the Prior Art
Thermal blanklets and heating pads are of course well known in the prior art. Generally, thermal blanklets more commonly include either a cooling or heating effect wherein most heating blanklets or pads incorporate the use of electrical resistance elements disposed thereout the area of the blanket. Similarly cold applicator type pads or blankets are commonly used in the medical field and frequently include a flexible plastic package containing two chemicals which when mixed together absorb heat. The chemicals are frequently packaged on either side of a rupturable membrane so that the application of the pressure to the exterior package ruptures the membrane and causes the fluids to mix and produces the heat absorbing reaction. Alternately, and more expensively, cooling pads are used through the application of a compressor, refrigerant condensing and evaporator coils. It is obvious that the above type cold pads or blankets are heavy and cumbersome and therefore not as practical or variable as the structure of the present invention.
With reference to heat type thermal blankets and again in the medical field, structures have been proposed in which a warmed or heated fluid circulate through a duct in the pad or blanket. Such structure is attempted to overcome the obvious inefficiencies and disadvantages concerned with the structures involving heating resistance wires embedded in the blanket or pad.
It is recognized that the use of fluid in a both a heating and cooling thermal blanket or pad is much desirable over the aforementioned prior art structures. However, such a structure does include certain disadvantages. The U.S. Pat. No. 3,894,213 to Kumar and Brown, U.S. Pat. No. 3,967,627 are examples of prior art structures which while operational appear to be bulky, less than reliable and do not have certain safeguards involved with the application of selected and variable temperature ranges which would be highly desirable.